High-throughput technologies can be used to infer transcriptional hierarchies, but reconstruction of regulatory network models requires experimental validation of inferred regulatory connections. Shown at the top are representative examples of microarray expression profiles,⁷³  ChIP-Seq TF binding maps,⁷⁴  and single cell expression analysis,⁴⁷  which can all be used to infer regulatory hierarchies. The bottom part of the figure illustrates the importance of follow-up functional experiments such as perturbation and high-throughput transcriptional assays^39,40  to validate inferred regulatory connections.